A proposal for CVD growth of 15R-SiC by observing the etch pits on 15R-SiC (0 0 0 (1)over-bar) C-face

As grown Acheson crystals of 15R-SiC and 6H-SiC were etched by molten KOH. Etch pits peculiar to each polytype were observed both on C-face and Si-face of etched crystals. The inside of etch pit on the C-face was flat. Etch pits on 6H-SiC showed six-fold symmetry, and etching rate toward six equivalent <1 1 (2) over bar 0> was the fastest. In case of 15R-SiC, etching rate toward [1 (1) over bar 0 0] was Faster than that of [(1) over bar 1 0 0], and etch pits showed three-fold symmetry. Etching rate anisotropy between [1 (1) over bar0 0] and [(1) over bar 1 0 0] of 15 R-SiC was explained by the number of dangling bonds per edge atom. Though the chemical vapor deposition (CVD) growth of 15R-SiC has been conducted on Si-face 8.0degrees off-oriented toward <1 1 (2) over bar 0>, [1 1 (2) over bar 0] and [(1 1) over bar 2 0] might not be equivalent in 15R-SiC. If the crystal grew at near-equilibrium condition, the difference between off-orientation toward [1 1 (2) over bar 0]and[(1 1) over bar 2 0]might become obvious. Further research is necessary for the CVD growth of 15R-SiC to achieve high quality crystals. (C) 2002 Elsevier Science B.V. All rights reserved.